1. Field of the invention
The present invention relates to a large aperture ratio wide-angle photographic lens system and, more particularly, to a large aperture ratio wide-angle photographic lens system comprising an aspherical surface.
2. Description of the prior art
The lens system desclosed in Japanese published examined patent application No. 10049/80 is known as a wide-angle photographic lens system having a lens configuration which resembles the lens configuration of the lens system according to the present invention. Said known lens system has the field angle of 84.degree. and aperture ratio of F/1.4. However, in said known lens system, the aspherical surface is provided to a lens for which a material with a high refractive index is used and, therfore, it is necessary to form the aspherical surface on a glass material. This means that it is not easy to manufacture the lens and, consequently, the cost becomes high.